This invention relates generally to fire protection systems and, more particularly, to fire protection systems in which a plurality of individual fire suppressor units are simultaneously activated to extinguish a fire.
Certain fire protection systems employ a plurality of strategically located suppressor units, each including an extinguishant filled vessel and an electrically operated release mechanism for inducing discharge of the extinguishant in response to detection of a fire. When simultaneous operation of all suppressor units is desired, the system is provided typically with a control circuit that produces coincident activation of all release mechanisms. In such systems, it is common technique to electrically supervise the electric integrity of the release mechanisms by providing and monitoring a trickle current through a series connection thereof. Although this series supervision establishes a constant knowledge of release mechanism integrity, there remains the possibility that a single release member failure will cause failure of the entire series system. In addition, even a detected failure of a release mechanism can prevent system operation if the detected failure occurs coincidentally with a demand for system actuation.
Partial solutions to this problem are provided in U.S. Pat. Nos. 3,917,001 and 3,952,809. The systems disclosed in those patents include circuits for switching the release mechanisms from a series to a parallel arrangement a short period after system activation is initiated. Although a substantial improvement over the prior art, the disclosed systems do not insure activation of specific system units having dysfunctional individual release mechanisms. In addition, these prior systems can be rendered completely inoperable by certain conditions such as an open circuit in a control line between a control panel and a series of suppressor units.
The object of this invention, therefore, is to provide a more reliable fire protection system of the type employing a plurality of individual suppressant units all having electrically operated release mechanisms adapted for coincident activation.